Help Identifying Engine
 

I'm trying to help a friend identify an engine block that's in a 76 Stringray. I beleive it to be from a 74 Caprice 400.

Partial Vin: 14Y131296
Engine Code: 0402CTD
Cast Code: GM 330817

So far I think this is a Small Block 400ci, from a 74 Caprice, 4 Barrel. 175 HP

When looking for parts like at O'reilly i see two diff options, a 6556cc, and 6555cc for the 6.6L 74 Caprice. Can i get more specific on this block? whats the diff? we are both amateurs when it comes to cars


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